OpenVPN can access in-vpn IPs bot not Internet

So its an old topic..

After two years of no-problems I upgraded from Ubuntu 18.04 to Ubuntu 20.04 and now the Internet Connection over OpenVPN is not running anymore, so I have

• IP Forwading Enabled

$ sysctl net.ipv4.ip_forwardnet.ipv4.ip_forward = 1

• I can connect to the VPN Server and access other internal IPs over VPN.

• My OpenVPN server itself can reach the Internet:

$ sudo tracepath 8.8.8.8 -n 1?: [LOCALHOST]                      pmtu 1500 1:  192.168.56.9                                          0.144ms  1:  192.168.56.9                                          0.099ms  2:  < my public IP>                                       0.191ms  3:  87.186.182.25                                         2.849ms 

• My client traffic is also getting routed to the tun0 interface:

... but I do not see a package comming back (<). Am I missing something in iptables (maybe)?

Firewall:

$ sudo iptables -LChain INPUT (policy ACCEPT)target     prot opt source               destination         ACCEPT     all  --  anywhere             anywhere            Chain FORWARD (policy ACCEPT)target     prot opt source               destination         DOCKER-USER  all  --  anywhere             anywhere            DOCKER-ISOLATION-STAGE-1  all  --  anywhere             anywhere            ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHEDDOCKER     all  --  anywhere             anywhere            ACCEPT     all  --  anywhere             anywhere            ACCEPT     all  --  anywhere             anywhere            ACCEPT     all  --  anywhere             anywhere            ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHEDACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHEDChain OUTPUT (policy ACCEPT)target     prot opt source               destination         ACCEPT     all  --  anywhere             anywhere            Chain DOCKER (1 references)target     prot opt source               destination         Chain DOCKER-ISOLATION-STAGE-1 (1 references)target     prot opt source               destination         DOCKER-ISOLATION-STAGE-2  all  --  anywhere             anywhere            RETURN     all  --  anywhere             anywhere            Chain DOCKER-ISOLATION-STAGE-2 (1 references)target     prot opt source               destination         DROP       all  --  anywhere             anywhere            RETURN     all  --  anywhere             anywhere            Chain DOCKER-USER (1 references)target     prot opt source               destination         RETURN     all  --  anywhere             anywhere